Structural members to be used in aircaft are preferably made of composite material where possible so as to gain the advantages of lightness of weight and ease of manufacture compared to those made of metal. Further, the design to costs targets for aircraft made of composite materials requires a significant reduction in fabrication costs.
Such structural members made of composites may be of the sandwich construction, however, a weight saving thereover can be made by fabricating the structural member from bonded plies of composite material having stiffener beads therein.
The stiffener beads of the prior art produce the advantages of lightness of weight, however, in view of the shape of the prior art stiffener beads, the composite material ply had to be darted and spliced during the ply lay-up process. This was a very time consuming process which produced a weak section in the structural member at the area of the darting and splicing and which prevented visual inspection of the ply bonding.
To overcome the requirement for darting and splicing of each composite ply required in fabrication of the prior art stiffener bead structural members, we have developed such a structural member in which a uniquely shaped stiffener bead and a unique fabrication process permits the fabrication of the structural member without the need for ply darting and splicing.